CsCheck vs QuickTheories

CsCheck is a free C# random testing library inspired by QuickCheck, intended for self-hosted use. Its composable Gen classes shrink generated cases automatically without Arb classes, and a shrunk case includes a seed that can reproduce a failure. The library supports random, model-based, metamorphic, performance, specification, regression, parallel and equality testing. Parallel tests compare outcomes with possible linearizations and support shrinking. Specification checks can enumerate reachable state spaces exhaustively or sample them, and can test whether declared faults are caught. Its Faster function statistically compares methods to assess whether one is faster and can run as a normal test across platforms. Example tests use TUnit, though the project says CsCheck can be used with any testing framework. The project page reports more than 1,000 F# tests using CsCheck in MKL.NET. NuGet lists version 4.9.1 and installation instructions for the .NET CLI and PackageReference. The project notes that generic recursion limits AOT compatibility; its Dbg module is temporary and may change between minor versions.

QuickTheories is a free, open-source property-based testing library for Java 8. It checks general properties and invariants by generating random valid inputs, then automatically searches for smaller or simpler values that still fail a property. The library reports the seed for a falsified property, and tests can use fixed seeds for deterministic runs. Its generator DSL creates common Java types, constrains values, and combines or converts generators for custom types. QuickTheories works with JUnit, TestNG, and other test frameworks; `checkAssert` supports assertion libraries such as AssertJ and Hamcrest. The `forAll` API handles theories over one to four generated values. System properties configure seeds, example counts, and shrink attempts, while named profiles can reuse settings. An experimental coverage feature targets new code paths, but may reduce performance by about 10% and interfere with JaCoCo or other coverage systems. The project uses the Apache-2.0 license.